Pair of positive holding and pulling pincers for weaving looms

Abstract: A part of positive holding and pulling pincers for insertion of weft threads of a fabric in a weaving loom, each pincer comprising: a support containing said pincer and fixed to a conveyor belt; a flat spring (16) having one end cooperating with a plate (15) and pivoted in its median portion on a pin (20); a means for approaching said end to or withdrawing it from the fixed plate (15) comprising a moving cursor (11) provided with an oblique groove (11a) in which slides the end of the spring (16); a means for blocking the moving cursor (11); a lever (3) providing a rectilinear advancing and backing movement to said cursor (11); and a means of releasing said blocking means.

Description: The present invention relates to a pair of positive holding and pulling pincers for weaving looms. Specifically the present invention relates to a pair of positive holding and pulling pincers for insertion of weft threads of a fabric in a weaving loom adopting belt processing or other known systems. Positive pincers for weaving looms incorporating weft gripping mechanisms are known and generally used in the industry. Said pincers comprise thread gripping devices activated for opening and closing through suitable mechanisms provided on the machine outside said pincers. Known pincers therefore require movement control systems which are very costly and complicate to regulate and also require rather long response times for opening and closing of said pincers. Consequently looms adopting said conventional pincers are relatively slow and their productivity is not very high. FR-A-1 480 561 discloses a pair of positive pincers for insertion of weft threads of a fabric in a weaving loom comprising a holding pincer and a pulling pincer moved by a conveyor belt having a rectilinear, alternating and horizontal movement and provided with a thread blocking device and means for opening and closing said blocking device. The purpose of the present invention is to overcome the shortcomings and limitations of presently known pincers. In its more general aspect the present invention permits solving the above shortcomings by means of a pair of improved holding and pulling pincers in which opening and closing of the weft blocking device takes place by means of a very simple mechanical system provided in said pincers and activated by a striker plate fixed on the loom. Weaving looms provided with the pincer pairs of the present invention exhibit a considerable increase in speed and productivity. Accordingly the subject matter of the present invention is a pair of positive pincers for insertion of the weft threads of a fabric in a weaving loom, comprising; a holding pincer and a pulling pincer fixed to a support and moved by a conveyor belt provided with a rectilinear, alternating and horizontal movement; each pincer comprises: a flat spring or rod having one end co-operating with a plate fixed to the support, said spring or rod being pivoted in its median portion on a pin fixed to said support; a means for approaching said end to or withdrawing it from the fixed plate, said means comprising a moving cursor provided with an oblique guide groove in which slides the end of the spring or rod opposite that co-operating with the fixed plate; a means of blocking the moving cursor; a first lever operated by a moving striker plate of the loom to give a rectilinear advancing and backing movement to said cursor and to release said blocking means in the advancing phase of said cursor; and a means of releasing said blocking means in the backing phase of the cursor. The construction and functional characteristics of the pair of positive holding and pulling pincers in accordance with the present invention are set forth in the description of an embodiment thereof given below by way of non-limiting example with reference to the annexed drawings in which: FIG. 1 shows schematically a side view of the holding pincer with the weft gripping device open and ready to block the thread, FIG. 2 shows schematically a side view of the holding pincer with the weft gripping device closed, FIG. 3 shows schematically a side view of the holding pincer with the weft gripping device closed and in the position immediately before release of the weft, FIGS. 4a-b show schematically the side and top views of the pulling pincer with the weft gripping device open and ready to block the thread yielded by the holding pincer, FIG. 5 shows schematically a side view of the pulling pincer with the mechanisms positioned in such a manner as to close the gripping device on the thread, FIGS. 6a-b show schematically the side and front views of the positioner and the element with cam of the pulling pincer, and FIG. 7 shows the detail of A of FIG. 4b. With reference to figures 1, 2 and 3 the holding pincer, indicated by P, is mounted on a support fixed on a conveyor belt provided with a rectilinear, alternating and horizontal movement (support and conveyor belt not shown because of known conventional type). Said pincer P comprises a cursor (1) moving on horizontal guides formed on the support and provided with a first guide slot (1a) and a second blocking slot (1b) with relating striker (4) and countersink (5). A second cursor (11) provided with an oblique groove (11a) is integral with said first cursor (1) through a rod (12). A coil spring (18) is fitted on said rod (12) and is arranged between the second cursor (11) and a guide element (22) for the rod (12) fixed to the support. A flat spring (16),having one end for blocking the weft thread, is is provided with a first plate (14) fixed in the intermediate position and a second plate (13) fixed to the end opposite the blocking end. The first plate (14) is pivoted on a pin (20) fixed to the support and the second plate (13) is provided with a rung (13a) running in the oblique groove (11a) of the second cursor (11). The blocking means of the moving second cursor (11) comprises a lever (2) pivoted in its median position on a pin (21) fixed on the support and arranged aligned in front of blocking slot (1b). Said lever (2) has one end (2a) shaped and insertable in the blocking slot (1b) and the opposite end (2b) rested on a cam (7). A flat spring (6) ensures contact of said end (2b) of the lever (2) with said cam (7). With said cam (7) is integral a shaped body provided with two beaks (8,9). A striker plate (17) fixed on the loom bucks against each of said beaks (8,9) during advancing and backing movement of the pincer P moved by the conveyor belt. An elastic means comprising a coil spring (19) fitted on a rod (10), which is guided by a guide element (24) fixed on the support, acts acts on the shaped body to hold in position the two beaks (8,9). A lever (3) pivoted on the pin (23) fixed on the support is provided with a rung (3a) inserted in the guide slot (1a) of the first cursor (1) and slides in said slot. A plate (15) fixed on the support is arranged opposite the blocking end of the flat spring (16) and cooperates therewith to block the weft thread. Operation of the holding pincer P is as follows. The holding pincer P is shown in FIG. 1 in the position ready to receive the weft thread with the first cursor (1) struck against the fixed element (22) and the blocking end of the flat spring (16) far from the plate (15). When the lever (3) is pressed downward (by a moving striker plate of known type not indicated in the figures) the first cursor (1) is pushed by the rung (3a) inserted and sliding in the guide slot (1a) and is backed from its initial position, loading the spring (18) and causing the shaped end (2a) of the lever (2) to emerge from the blocking slot (1b). Said shaped end (2a) arranges itself outside the first cursor (1) blocking it in the backed position and preventing it from returning to the initial position (see FIG. 2). The end (2b) of the lever (2) is held by the flat spring (6) in contact with the narrow part of the cam (7) (see FIGS. 1 and 2). The position of the cam (7) is ensured by the elastic means (19). Backing of the first cursor (1) also drags the second cursor (11) and causes upward shifting of the second plate (13) following sliding of the rung (13a) in the oblique groove (11a). In this manner the flat spring (16) rotates on the pin (20) and its blocking end arranges itself against the plate (15) blocking the weft thread introduced when the lever (3) was pressed. With the thread blocked the pincer P thus runs being constrained to a conveyor belt or rack in the direction indicated by the arrow F1 carrying the weft thread towards the central part of the loom where the striker plate (17) is provided. When the striker plate (17) meets the beak (9) of the shaped body it causes it to rotate (see FIG. 3). This movement of the shaped body causes shifting upwards by means of the cam (7) of the end (2b) of the lever (2). The shaped end (2a) of said lever arranges itself in a position corresponding to the slot (1b) and penetrates therein resting on the countersink (5). The cursor (1) is no longer blocked and hence is free to return to its initial position dragging with it the second cursor (11). This movement causes downward shifting of the second plate (13) following sliding of the rung (13a) in the groove (11a), withdrawal of the blocking end of the flat spring (16) from the plate (15) and then opening of the pincer and release of the weft thread and its possible transfer to the pulling pincer without the risk of breakage and fraying. The pincer P entrained by the conveyor belt or rack then returns, moving in the direction opposite that of the arrow F1,to the initial end of the loom and thus the striker plate (17) meets the beak (8) causing rotation of the cam (7) which is brought back to the starting position pushing the lever (2) to settle (as in FIG. 1) with its shaped end (2a) in the blocking slot (1b) of the cursor (1). The latter advances fully, recalled by the spring (18), achieving the full withdrawal of the end of the flat spring (16) from the plate (15). The pincer is now fully open and ready to again receive the weft thread. With reference to FIGS. 4, 5, 6, and 7 there is now described the pulling pincer indicated by T which is also the subject matter of the present invention. Said pulling pincer T comprises a cursor (31) moving on horizontal guides formed on the support and provided with a guide slot (31a) and a projection (31b). Said cursor (31) is also provided on one side with a first rod (34) and on the opposite side with a second rod (32). On the first rod (34) is fitted a coil spring (37) which bucks between a guide element (51) of the rod (34) fixed on the support and the side surface of the cursor (31). The second rod (32) is provided with an intermediate positioning ring (42) or annular band and a right angle end (33). On said second rod (32) are fitted two coil springs (45,46) of which one spring (45) arranged between said positioning ring (42) and the end (33) and the other spring (46) between the surface of the cursor (31) and the positioning ring (42). A lever (36) is hinged at one its end in correspondence on near the end (33) of the second rod (32) and is in contact with the projection (31b) of the cursor (31),in correspondence of end, and with the surface of a cam (40) in its median part. A flat spring (35) acts on the lever (36) holding it in steady contact with the surface of the cam (40). Said positioning ring (42) is provided on two opposite faces with two tabs (42a). Integral with the cam (40) is a shaped body comprising an arm element (41) and a pair of guides (43,44) which are in contact with the two tabs (42a). The end (33) of the second rod (32) is provided with an oblique guide groove (33a). A rod (48) pivoted in its median position (39) is provided at one end with a pin (48a) inserted and running in the groove (33a). A lever (38) pivoted on a pin (52) fixed to the support is provided with a rung (38a) inserted and sliding in the guide slot (31a) of the cursor (31). A spring (50) is inserted in the free end of the rod (48) to ensure blocking of the weft thread. A plate (49) fixed on the support in correspondence of the free end of the rod (48) co-operates with the latter for blocking the weft thread. The loom is provided with a projection (47) which actuates closing of the pincer T. Operation of the pulling pincer T of the present invention is as follows. The pulling pincer T is shown in FIGS. 4a-b in the open position ready to receive the weft thread from the holding pincer P. In this position the lever (38) has been pressed downward (by a moving striker plate of the loom of known type and not shown in the FIGS.) causing backing of the first rod (34) and the cursor (31) and loading of the spring (37). Together with said cursor (31) are also backed the second rod (32) with the positioning ring (42) and the front end (33) of the second rod (32). In this position the rod (48), constrained to the groove (33a) of said end, end, rotates around the fulcrum (39) withdrawing its free end from the plate (49). Simultaneously the arm element (41) of the shaped body integral with the cam (40) is found turned downwards. The lever (36) rests on the narrow part of the cam (40) forced there by the spring (35). The free end of said lever (36) meets the projection (31b) of the cursor (31). Moving in the direction of the arrow (F2) the pincer T contacts the rung (47) which pushes upwards the arm element (41) (see FIG. 5). The cam (40) rotates and raises the lever (36) whose free end is no long struck with the projection (31b). The spring (37) thus advances the cursor (31) and hence the rod (32), the positioning ring (42) and the front end (33). In this condition the positioning ring (42) rotates by 90° the arm element (41) and anything integral therewith by acting on the guide (43). The lever (38) rises upwards again while the end of the rod (48) arranges itself against the fixed plate (49) blocking the weft thread carried there and yielded by the pincer P. The pincer T then moves again towards the end of the loom where the lever (38) is again pressed and the entire system returns as in FIGS. 4a-b with the free end of the rod (48) far from the fixed plate (49), the weft thread released and the arm (41) directed downwards. The pincer T is now ready to again receive the weft. The holding and pulling pincers can be installed even individually on weaving looms. Both of said pincers, or one or the other of them, could also find application on weaving looms originally provided with non-positive pincers. Lastly, it is understood that structural reversals or alternative locations of the components constituting as a whole the holding and pulling pincers of the present invention are possible.

Claims: A pair of positive pincers for insertion of weft threads of a fabric in a weaving loom, comprising a holding pincer (P) and a pulling pincer (T) fixed to a support and moved by a conveyor belt provided with a rectilinear, alternating and horizontal movement; said princers being provided with a thread blocking device and means for opening and closing said blocking device, characterized in that each pincer comprises: a flat spring or rod (16,48) having one end co-operating with a plate (15,49) fixed to the support, said spring or rod being pivoted in its median portion on a pin (20,39) fixed to said support; a means for approaching said end to or withdrawing it from the fixed plate (15,49), said means comprising a moving cursor (11,31) provided with an oblique guide groove (11a,33a) in which slides the end of the spring or rod (16,48) opposite that co-operating with the fixed plate (15,49); a means of blocking the moving cursor (11,31); a first lever (3,38) operated by a moving striker plate of the loom,to give a rectilinear advancing and backing movement to said cursor (11,31) and to release said blocking means in the advancing phase of said cursor (11,31), and a means of releasing said blocking means in the backing phase of the cursor (11,31). The pair of pincers according to claim 1, characterized in that the holding pincer (P) comprises: a first cursor (1) moving on horizontal guides formed on the support and provided with a first guide slot (la) and a second blocking slot (1b) with relating striker (4) and countersink (5); a second cursor (11), provided with an oblique groove (11a), integral with said first cursor (1) through a rod (12); a coil spring (18) fitted on said rod (12) and arranged between the second cursor (11) and a guide element (22) for the rod (12) fixed to the support; a flat spring (16), having one end for blocking the weft thread, provided with a first plate (14) fixed in the intermediate position and a second plate (13) fixed to the end opposite the blocking end; the first plate (14) being pivoted on a pin (20) fixed to the support and the second plate (13) being provided with a rung (13a) sliding in the oblique groove (11a) of the second cursor (11). The pair of pincers according to claim 1 or 2, characterized in that the blocking and releasing means of the holding pincer (P) comprises a second lever (2) pivoted in its median position on a pin (21) fixed on the support and arranged aligned in front of the blocking slot (1b); said lever (2) having one end (2a) shaped and insertable in the blocking slot (1b) and the opposite end (2b) rested on a cam (7) integral to a shaped body provided with two beaks (8,9); said shaped body rotating in one direction or in the opposite one when each beak (8,9) meets a strike plate (17) fixed on the central part of the weaving loom, thereby the shaped end (2a) of the lever (2) is settled into the blocking slot (1b) or arranged on the coutersink (5). The pair of pincers according to claim 3, wherein a flat spring (6) is provided to assure the contact of the end (2b) of the lever (2) with the cam (7). The pair of pincers according to claim 3, characterized in that an elastic means comprising a coil spring (19) fitted on a rod (10), and guided by a guide element (24) fixed on the support, acts on the shaped body to hold in position the two beaks (8,9). The pair of pincers according to anyone of the preceding claims, wherein the first lever (3) is pivoted on a pin (23) fixed on the support, it is provided with a rung (3a) inserted in the guide slot (1a) of the first cursor (1) and sliding in said slot, and it is moved by the moving striker plate of to the loom. The pair of pincers according to claim 1, characterized in that the pulling pincer (T) comprises: a cursor (31) moving on horizontal guides formed on the support and provided with a guide slot (31a), a projection (31b), a first rod (34) on its side and a second rod (32) on the opposite side; a coil spring (37) fitted on the first rod (34) and arranged between a guide element (51) of the rod (34) fixed on the support and the side surfa ce of the cursor (31); an intermediate positioning ring (42) or annular band and a right angle end (33) provided on said second rod (32); an oblique guide groove (33a) provided on said right angle end (33); two coil springs (45,46) of which one spring (45) arranged between said positioning ring (42) and the end (33) and the other spring (46) between the surface of the cursor (31) and the positioning ring (42); a second lever (36) hinged at one its end in correspondence or near the end (33) of the second rod (32) and in contact with the projection (31b) of the cursor (31), in correspondence of its end, and with the surface of a cam (40) in its median part; two tabs (42a) provided on the two opposite faces of the positioning ring (42); a shaped body comprising an arm element (41) and a pair of guides (43,44), which are in contact with the two tabs (42a), integral with the cam (40); said rod (48) pivoted in its median position (39) and provided at one end with a pin (48a) inserted and sliding in the oblique guide groove (33a); the first lever (38) pivoted on a pin (52) fixed to the support and provided with a rung (38a) inserted and sliding in the guide slot (31a) of the cursor (31); said first lever (38) being moved by the moving striker plate of the loom, and a rung (47) fixed to the loom and acting on the arm element (41) to rotate the cam (40) whereby the end of the second lever (36) is disengaged from the projection (31b) of the cursor (31). The pair of pincers according to claim 7, wherein a flat spring (35) acts on the second lever (36) holding it in contact with the surface of the cam (40). The pair of pincers according to claim 7 or 8, wherein a spring (50) is inserted in the free end of the rod (48) to ensure blocking of the weft thread.

Inventors: MOIA IVO, MOIA, IVO
Applicants: MOIA IVO, MOIA, IVO
Application year: 1994
Main classification: D03D47
IPC codes: D03D47